1. Technical Field
The embodiments described herein generally relate to methods for stabilising video images, and more particularly to stabilising video images in the presence of motion blur. The described embodiments also relate to an apparatus adapted for providing stabilised video images, and to a computer program product for performing the described methods.
2. Related Art
The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Techniques for the digital stabilisation of video sequences to remove the effect of unwanted camera motion are known in the art. For example, WO/2007/020569 discloses a method for removing unwanted camcorder movement, or jitter. In the method, a motion estimate between a previous frame and a current frame is made and subsequently the current frame is realigned to counteract this motion.
However, the use of such techniques can result in undesired artefacts being observed in the output sequence. For example, if a video sequence contains some frames which are blurred as a result of motion, then a “pumping” effect can be observed wherein isolated unfocussed frames are present in the sequence of otherwise focussed frames. This effect tends to be more obvious to the observer after stabilisation of the sequence has been implemented.
Deblurring of single still images is disclosed in, for example, R. L. Lagendijk and J. Biemond “Basic methods for Image Restoration and Identification”, Handbook of Image and Video Processing, Elsevier Academic Press, editor Al Bovik, SD Edition 2005. However, such deblur algorithms suffer from the problem that it is difficult to estimate from a single image the motion that caused the blurring in the image. Additionally, motion deblur algorithms are generally sensitive to problems caused by the presence of moving objects within the scene. As a result, artefacts are often observed in a deblurred image.
It is an object of the embodiments herein described to obviate at least some of the disadvantages described above.